Re: [PATCH 04/43] xfs: skip always_cow inodes in xfs_reflink_trim_around_shared

Darrick J. Wong
2025-02-07T04:22:08Z

On Fri, Feb 07, 2025 at 05:15:42AM +0100, Christoph Hellwig wrote:
> On Thu, Feb 06, 2025 at 12:13:51PM -0800, Darrick J. Wong wrote:
> > Hmm. So this is to support doing COW on non-reflink zoned filesystems?
>
> Yes.
>
> > How then do we protect the refcount intent log items from being replayed
> > on an oler kernel?
>
> There are no refcount intent log items for this case.

Er... right, there aren't any refcount log items because there's no
refcount btree. Looking through the rest of the code, though, the same
question about protection against recovery by old kernels applies to the
bmap intent item logged in xfs_zoned_map_extent. And I think it has the
same answer -- zoned storage is an incompat feature bit that's newer
than the bmap intent items, so we're protected.

I got there clumsily, but here I am :P
Reviewed-by: "Darrick J. Wong" <djwong@kernel.org>

--D